1. Field of the Invention
The present invention relates to rotary table apparatuses.
2. Description of the Related Art
Machining centers, such as the machining center 90 shown in the perspective view of FIG. 13, have conventionally been used for machining mechanical parts. The illustrated machining center 90 is provided with, for example, a worktable 91 that can move horizontally in the Z direction, and a column 92 that holds a tool T such that it is movable in a vertical plane formed in the X and Y directions. In this way, a degree of freedom of machining in three directions that are orthogonal to one another is achieved.
In recent years, to further increase the degree of freedom of machining, the worktable 91 is further provided thereon with a rotary table apparatus 95 having a placement surface that can rotate about two axes. In this way, the machining center is provided with 5 degrees of freedom of machining, thereby allowing for a more complicated processing.
The perspective view of FIG. 14 shows an example of the rotary table apparatus 95. The rotary table apparatus 95 has a rotary table 96 having a circular placement surface 96a on which a workpiece W is placed, a support rest 97 that rotatably supports the rotary table 96, and a base 98 that turnably supports both sides of the support rest 97. The rotary table 96 and the support rest 97 are each provided with a respective drive mechanism (not shown), and these drive mechanisms make the support rest 97 turn so as to tilt the placement surface 96a and/or make the rotary table 96 rotate so as to cause rotation of the placement surface 96a about its center, thereby allowing the tool T on the column 92 to work on the workpiece W placed on the placement surface 96a. (See, for example, pages 8-9 and FIG. 1 of JP 2004-160642 A.)
As shown in the figure, this type of rotary table apparatus 95 adopts a both-side support structure in which the support rest 97 is supported at both sides thereof. Therefore, it is difficult to reduce the size of the base 98, and due to this fact, such a rotary table apparatus 95 could only be installed on a large-scale machining center 90. Thus, it has been difficult to increase the degree of freedom in machining small-sized parts that are mainly machined in small-sized machining centers.